Water consumption in semiconductor fabrication is high, due largely to the substantial quantities of rinse water used on wet benches. Many chemical reagents and acidic solvents, such as H2SO4, HF or H3PO4, are used during the manufacturing process. Wet stations or wet benches are designed to remove chemical residue on the surface of wafers with deionized water.
Due to the wet bench's heavy water consumption, there is typically a reclamation system present designed to regenerate clean water from waste water discharged by the wet bench. Conventionally, the reclamation switch time of the wet bench is based on loose factory settings such as, for example: 200 seconds. When the wet bench is set to run a rinse recipe (e.g., Quick-Dump-Rinse (QDR) for 5 minutes), the waste water in the first 200 seconds is discharged and then the waste water after 200 seconds is conducted into the reclamation system for further regeneration. However, the reclamation rate is typically only 30%.
If the reclamation switch time of the wet bench is shortened to, for example, 100 seconds, the waste water discharged by the wet bench after 100 seconds will be rejected by the reclamation system because the residue present will exceed the maximum tolerance, producing a reclamation rate of even lower than 30%.